There are many ways to address a slope. Which one to choose for your property depends on a number of factors, including aesthetics, site conditions, and budget.
First, let’s distinguish between two major categories of erosion control: soft and hard. Soft solutions include any flexible infrastructure that helps keep soil in place. This includes the plants themselves, but there are also many types of materials available that supplement and augment the anti-erosion effect of plant roots. Hard solutions, as their name suggests, include the use of hardscape elements.
Here is a rundown of some of the best options we have found for steep slope erosion control in Georgia.
Best Soft Erosion Control Solutions For Georgia Properties
In general, soft solutions will entail a lower upfront cost than hardscape. Since budget is often a concern in erosion control, let’s take a look at the lower-cost options first.
Flexible Slope Reinforcements
The lowest-cost and usually the quickest erosion control solution for steep slopes is to use a reinforcement such as a woven mat, applied over seed.
There are many such products available from a number of manufacturers. Most use a combination of photodegradable synthetic combined with some sort of natural fiber, typically either straw or curlex (birch fiber). All of these degrade over time, giving the plants time to establish themselves and create a network of roots to hold the soil in place. This can happen in as little as 90 days to as long as years for something like a coconut fiber mat. There are also non-degradable synthetic mats that offer permanent erosion protection.
Typically, we hydroseed the slope with a drought-tolerant, hardy seed mix (usually including some of the plants we mentioned in our recent post on erosion control for Georgia slopes), and then apply the matting. If aesthetics are a high priority for your sloped area, you can include wildflowers such as black eyed Susan, cosmos, or a hardy wildflower mix into the seed mix to add beautiful color to your slope.
Wattles And Logs
The longer the distance water is allowed to flow unimpeded, the faster it runs. And the faster water runs down a slope, the worse the erosion tends to be. So we want to disrupt the flow as many times as we can.
One of the ways we do this is to use a system of coir logs (fiber rolls that literally look like life-sized logs) and/or straw wattles (long, 8-12” diameter snake-like fiber bags stuffed with weed-free straw) to slow down runoff on a slope. Wattles and logs act like check valves, slowing the flow, capturing loose soil, and letting the water soak into the soil instead of just running to the bottom.
Sometimes we use straw wattles or coir logs in conjunction with erosion control matting. All of these are stapled or staked to the slope to hold them in place. Typically we will prep the slope with skid steers or dozers, then hydroseed, then apply the mats, and put the wattles or coir logs on last. The steeper and longer the slope, the more the erosion potential, and the more these things help out.
Armoring And Revetment Systems
A step beyond wattles and logs is to use a system of commercially available flexible mats made from concrete products connected by wire, or synthetic polymer plastic material. We combine these systems with vegetation planted into the cavities between the mesh. This can be seeded or plugs, groundcovers or grassy plants.
Flexible revetment mats, such as the RevetMax™ products from North American Green, are a harder, more permanent armoring for higher velocity, more concentrated flows. They work well in drainage channels and for wetland mitigation applications such as shorelines where they are exposed to water flow, as well as on steep slopes.
Steep Slope Erosion Control: Hard Solutions
All of the above solutions are best for slopes up to 45 degrees. Anything steeper than that, and we have to go to a hard solution.
The next step up from soft erosion control solutions is rip rap. This material is just large pieces of uncut natural stone or concrete rubble. Here in Georgia it’s most often granite. It comes in various grades and sizes, starting about the size of a football and going up from there. Rip rap is the most cost effective hard solution.
It’s worth noting that not all concrete rubble is suitable to use in the landscape. Some may be contaminated. When you start using construction debris it must be done in compliance with environmental regulations, so check with the Georgia EPA or the Corps of Engineers first if you think you want to go that route.
Rip rap is typically scattered across a slope without any particular order; it’s simply large stones placed on slope. You can seed and let things grow in between the rocks, or choose not to seed at all. A lot of times we will lay smaller stone in between large pieces of rip rap to fill in the gaps.
This material is very effective at erosion control, especially in shoreline applications, ditches, and other places where the potential for water action on the soil is extreme. However, it does allow some movement of water and soil between the stones. We advise and prefer clients to apply permanent woven mat underneath.
While rip rap is certainly useful, it’s not particularly attractive, and isn’t suitable for the very steepest slopes. For very steep slopes, retaining walls are excellent. While more expensive than other options, retaining walls offer many advantages both in engineering and aesthetics. But that’s a topic all its own, which we will address in a future post.
Georgia Erosion Control Contractor, At Your Service
Looking for erosion control companies in Georgia or the Southeast? Give us a call. We’d be happy to discuss suitable and cost effective options for your property. You can reach our East Dublin office at 478-272-3878, or call our Macon folks at 478-750-7733. Or, click here to contact us online. We look forward to serving you!